Senator Obama has been saying that it's his opponent who is guilty of what he calls slash and burn tactics and both of the candidates are unveiling negative ads in these final days before Tuesday's primary.

He is saying that Senator Clinton is really going at him with what he calls slash-and-burn politics, saying that she's throwing everything and the kitchen sink at him, saying that that is distracting from debating the real issues.

Personally, I've never been much into slash simply because I'm usually not into any pairing that's not canon (which says a lot about mainstream media and brings up the question of how exactly to define 'slash', but anyway), so I can't say much about that sort of trend in slash in general.

You're missing the usage among fanfiction writers. "Slash" there denotes the category of fanfic that brings characters together as lovers -- common pairings are Snape and Harry in Harry Potter fanfic, Kirk and Spock in Star Trek fanfic, Sheppard and McKay in Stargate: Atlantis fanfic. The term derives, I believe, from the typographical / -- people often write"Snape/Harry" or "K/S," for example.

Slash in this sense is also a verb (to slash Characters A and B). And it appears in compounds such as femslash (slash fic that pairs women; the "default" of slash is male/male pairings).